Cognitive-behavioral therapy (CBT) is a partially effective treatment for bulimia nervosa. CBT helps reduce rates of binging and purging and between 40-60% of individuals treated with CBT recover. Increasingly, internet-based approaches to health care are gaining popularity and showing efficacy in the treatment of a variety of psychiatric disorders as well as obesity. We propose to develop an rich, vivid, and interactive electronic form of CBT (available on web and CD-ROM) that enables self-monitoring, provides helpful psychoeducation on the facts about bulimia nervosa; clearly introduces the basic concepts and techniques of CBT; provides rich and vivid examples of techniques; and provides individualized and interactive exercises for practicing CBT principles. This project is one facet of a programmatic strategy to enhance the available repertoire of information-technology enhanced treatment approaches for individuals with eating disorders. We have already produced and herein present preliminary results of a CD-ROM-based CBT program for binge eating disorder and obesity (POWER: Preventing Overweight With Exercise and Reasoning) and a second family-based program for childhood overweight. Once completed and tested, this internet-based program for bulimia nervosa will have multiple uses. It could be used as a first step in a program of stepped care in which individuals can experience the basics of CBT at the privacy of their own computer. For some, this program may suffice for treating their bulimia nervosa. For others, the true value of this program will be as an adjunct to traditional CBT or as a source for booster sessions after traditional therapy ends. This program will be appropriate for late adolescent and adult women (with special user selected modules for men) of all races and backgrounds. We will implement a rigorous beta-testing procedure by health care providers knowledgeable about the treatment of bulimia nervosa and by patients with current bulimia nervosa. At the end of the R21 we will have a high-quality product that will be ready for testing in clinical trials.